Its perfectly legal to use ingame gold to buy GM of a guild.

When my first guild fell through I got the 250K or so I paid back from customer service, they said buying the guild was legal but clearing out the bank is not.

Just don't touch the Bank.

I am looking to buy even more guilds and have 400K on my trader.

Well I hit 5 million and posted on the wow general forum I should know soon if it is a wow first. HIt my sig for SS.